1. Field of the Invention
The present invention relates generally to heat treatment of oysters, and more particularly, to a heat treatment process to be employed with oysters while the oysters remain in their natural shell. This process is employed to reduce and eliminate harmful bacteria found in oysters, such as Vibrio vulnificus.
2. Description of the Prior Art
While sea foods are generally considered healthy and safe to consume, concerns about the safety of eating raw oysters is widespread. Bacteria, such as the autochthonous estuarine bacterium Vibrio vulnificus, may be transferred from the marine environment to the oyster. This bacterium has been shown to cause primary septicemia, gastroenteritis and other disorders in humans. Septicemia generally leads to secondary cutaneous lesions and necrotic ulcers of the extremities, approximately sixty percent of all known cases result in fatalities. Other bacterium may also be pathogenic and may be introduced to the human through consumption of raw oyster meat. Some 10-15 deaths a year nationwide are attributed to oyster consumption, most of the oysters being harvested in the Gulf of Mexico during the summer months. Those who are immune compromised, suffer from hepatitis, other liver ailments, or diabetes may be more susceptible to the harmful effects of the Vibrio vunificus bacterium. The Gulf Coast is the major producer of oysters, providing between 12 and 20 million pounds annually, well above half the national supply.
The Vibrio vulnificus are located in oysters, and primarily this method will be utilized to destroy this pathogenic organism to permit the harvesting of oysters during the warmer months and in warmer waters, especially in the southern United States, where it has been proposed by the Food and Drug Administration to suspend the harvesting of oysters during the summer months as a health precaution.
As a result of the above concerns, we began developing processes to destroy such bacteria. Our initial process as outlined in U.S. Pat. No. 5,679,392 heat treats oysters in their shell for their eventual serving raw on the half shell. This heat treatment process is utilized on oysters which have been bagged prior to immersion in a warm water bath. These oysters are immersed in water between a temperature of 43-60 degrees centigrade for a time period of 30-45 minutes. They are subsequently cooled, shucked and served on the half shell.
The new invention contemplates heat treating oysters in their shell as well, but without the bag. Also, the new invention contemplates a water bath of between 49-55 degrees centigrade for a time period of between of about 10-45 minutes depending on the size of the oysters, the temperature of the water, and the initial temperature of the oyster meat within the shell. The instant invention contemplates that the meat within the oyster shell must exceed a temperature of 49 degrees centigrade, yet not exceed a temperature of 53 degrees centigrade. Oysters which have been treated by the new process will be safe and be are able to be served at a raw bar in a raw state. However, it is mainly contemplated that oysters which have been treated by the instant process may be mechanically shucked and their meat packaged by conventional means. This will permit safe oyster meat to be available for commercial consumption on a large scale.
Thus, while the foregoing prior art indicates it to be known to use warm water to heat treat oysters while the oysters remain in their shell, the concept of treating such oysters without the bag has not been disclosed. Also, the specific internal meat temperature range which must be reached and not exceeded is not taught in the prior art. By eliminating the bagging step a significant cost and labor saving is realized. This process is also directed not only to permit a consumer to eat such a processed oyster on the half shell, but also contemplates the mechanical shucking and subsequent packaging of the treated oyster meat for the marketplace. The heat treatment temperature and time ranges for the various weight oysters permits the process to completely eliminate the Vibrio vulnificus bacteria from the oyster prior to the removal of its shell. Other advantages of the present invention over the prior art also will be rendered evident.